Mold temperature on the influence of the injection molding

A hot mold surface make plastic surface liquid for a long time, enough pressure in the cavity. If the cavity filling and appear in the frozen skin before hardening, cavity pressure can be soft plastic pressure on metal, then copy on the surface of the cavity are high. If, on the other hand, in low pressure into the cavity of the plastic suspended, no matter how short time, then it can cause slight contact with metal, is sometimes called the gate blotch.

For each kind of plastic and plastic parts, there is a mold surface temperature limits, more than the limit of one or more adverse effects may appear (for example: components can overflow flash). Mold temperature means higher flow resistance smaller. In a number of injection molding machine, this natural means faster through the water, the runner and cavity, because the injection flow control valve is not correct the change, filling faster will cause higher in the runner and cavity pressure effectively. May cause flash flash. Due to more hot model does not freeze the before the high voltage into the area of the plastic material overflow edge, molten material can flash flash around the ejector rod and overflow into the line clearance. This suggests that need good injection rate control, and some modern flow control programmer can do this, too.

Usually, mold temperatures will reduce the plastic layer in the condensation cavity in the morning, make molten material within the cavity flow more easily, thereby gaining more weight and better surface quality of parts. At the same time, the improvement of mold temperature will cause the parts increase tensile strength. Many moulds, especially engineering thermoplastics, running at a relatively high temperatures, if there is no heat preservation, mould lost into the air and the heat injection molding machine can be easily and shoot as much material loss of cylinder. So will die and heat insulation boards, if possible, will die surface heat insulation. If consider using a hot runner mold, try to reduce the hot parts and cooling of the heat exchange between the injection molded parts. This method can reduce the energy loss and the preheating time.

The need for temperature control

(1) the purpose of temperature control on the formability and as

Molded products appearance, material physical properties, the forming cycle, etc., the cavities temperature, effects of quite significant. General molding, mould kernel keep in low temperature, can improve the injection times is ideal, but with the shape of molded products (cavities structure) and finished product material about the forming cycle also send in must improve the temperature of mould kernel filling.

(2) to prevent temperature stress control

This product material for forming problem, this requirement only does the cooling speed. The cooling time is short, even if there is a part of hardening part is soft, still can avoid caused by uneven shrinkage stress. That is, the appropriate temperature control can on stress of cooling properties improved.

(3) the material forming the crystallization degree of adjustment for temperature control

Polysulfide ammonia (nylon), acetic acid number of polyester, polypropylene crystallization materials such as to adjust the degree of crystallization, and mechanical properties improvement, generally have higher temperature of mould kernel.轮架、工作台进给电机不能启动？